'78 1400 lost #3 cylinder

[monk-monk]

I bought a boat and it came with an 1150 on it...i knew that powerhead was bad...so i had a '78 1400 that has been on a stand for years...i did a powerhead swap...today at the lake, while doing the link & synch the motor lost the #3 cylinder...i could tell this because as i was rotating the flywheel i could here the piston dragging the cylinder wall...Im wondering what could caiuse this, could there have been a build up of rust on the cylinder wall...i removed the exhaust plate and observed the #3 piston and it is scored on the skirt of the piston, but the dome looks good...what is the biggest reason for losing a cylinder...??

 

[CVX20SPRINT]

Re: '78 1400 lost #3 cylinder

If the motor wasn't fogged before storage then you can be fairly sure that there would be rust in the cylinders and possibly the bearings(crank/rod)as well.It will have to be torn down to see how extensive the damage is.A little fogging oil can save alot of expensive repairs.IMHO that motor is well worth rebuilding.

 

[Faztbullet]

Re: '78 1400 lost #3 cylinder

If the "eyebrow" is not eroded it likely some sort of debris like vermin or insect was in carb and was ingested or possibly broke a reed...

 

[monk-monk]

Re: '78 1400 lost #3 cylinder

Thanks for the replies...i was concerned about putting that powerhead back in service after sitting so long...i rebuilt the entire fuel system, carbs, fuel pump, fuel lines etc..and before i ever started it, i did spray lube the cylinders through the spark plug holes and i filled the block with the fuel mix and hand turned the motor about 100 revolutions...i started it several times here at home on the muffs and it sounded good but it gave up pretty quickly at the lake...when i got it home and removed the exhaust plate i used a piece of plastic to push on the rings and the rings are free and have spring tension on them...i know its really hard to say exactly what happened, but sitting for 5 yrs surley didnt help any...i should have removed those exhaust plates and examined it before i ever started it...luckly i caught this very quickly so the damage has been held to a minimum...the timing was set right and fuel delivery was good...the problem developed between the cylinder wall and piston skirt...Just trying to learn something here...any thoughts are very much appreciated...

 

[Chris1956]

Re: '78 1400 lost #3 cylinder

Normally you need to overheat, run lean or detonate to score a cylinder. Since you rebuilt the carbs, it should be one of the other two.

How high an RPM did you get to and for how long, before she seized?